With the growth of the Internet society in recent years, computer equipment, communications environment and interfaces have become capable of operating at higher speeds in broader bands and, hence, the amount of user-accessible digital picture information is increasing steadily in various fields; for example, various types of picture data are being accumulated in large amount here and there. Increasing importance has been attached to the art of accessing such massive amounts of information and quickly searching for a desired portion of a picture.
For a user to extract a user's desired image from a scene of a sport picture of, for example, tennis, methods of recognizing the substance of an image, such as “successful passing shot” and “successful smash”, are conceivable to be adopted. Such methods include methods of recognizing the substance of such an image by manually inputting a “successful passing shot” section, a “successful smash” section and a like section of picture information one by one, or by extracting positions of respective of a ball, players and court lines and totally judging a change with time in spatial correlations among the extracted positions with use of a computer.
The method of image recognition based on manual input, however, involves a problem of increased labor costs and a problem of heavy burden on the operators which arises when the contents processing takes a long time, though the substance of an image can be reliably recognized. On the other hand, the method of automatic image recognition with a computer has such an inconvenience that if picture information is the only subject for processing, a failure occurs to trace a ball when the ball is overlapped or hidden by a player, net or the like, so that an important position and time cannot be specified in a portion of picture information, thus resulting in a failure to detect an event to be recognized or in erroneous image recognition.